It is well known that hydrophobic finishes for fibers are based on aluminum and zirconium salts of long-chain carboxylic acids. Such hydrophobic finishes are described, for example, in E. B. Higgings, Waterproofing and Water Repellance, J. L. Moilliet, Editor, Elsevier Publishing Co., Amsterdam, p. 188, 1963. However, the finishes do not exhibit wash permanency due to the alkali solubility of the compounds (i.e. the ability of a finish to remain on the surface of a substrate after several wash cycles).
A paraffin-based finish described in DE 24 20 971 is currently preferred for use as an extender for polymer fluorocarbon finishes. This paraffin-based finish requires addition of salts or polymers in order to achieve adequate stability and wash resistance. A high application weight and the related changed hand and water vapor transport represent drawbacks of these finishes.
Metal compexes of chromium and pyridinium complexes of long-chain aliphatic compounds are regarded with increasing criticism with respect to toxicological problems. Similar concerns apply to formaldehyde resins, which impart good water repellency to the substrate, but tend to release formaldehyde.
Fluorinated copolymers based on polyacrylate (methacrylate) copolymers that are used as oleophobic and hydrophobic finishes such as in combination with cationically modified polyurethanes are described in DE 39 39 341. The specific application method of the finish depends on the fiber material. Also, organic solvents of the partially fluorinated copolymer must be used for application of these partially permanent finishes. In addition, the application of several fluorocarbon layers to the substrate is required, as well as the addition of various auxiliaries.
The combination of a perfluoroalkyl group-containing compound with quaternization products of basic fatty acid amides is described in DE 36 20 033. The use of fluoropolymers required for the finish is distinctly reduced by using this combination. However, for optimal hydrophobicity values during finishing of cotton/polyester at least 10 g/l are required. As a result significant amounts of additional products are also required including, for example, 60 g/l of synthetic resin, 4 g/l of catalyst or 20 g/l of fatty acid amide.
A modification of polyamide soft with 10 g/l acrylate copolymer and, for example, 10 g/l of a polycationic compound known as a paper glue component is proposed in EP 0 008 761. A good water repellant effect is achieved here, but water breakthrough is not satisfactory.
Oleophobic finishes for textiles cannot be obtained when an exclusively hydrophilic compound containing perfluoroalkyl groups is used. A hydrophobic and oleophobic effect can only be achieved in a combination of acrylate (co)polymer and fatty acid amide. An extender must be added in this case to improve permanence.
The use of low-molecular weight fluorocarbons (perfluoroalkanoic acids and their chromate complexes) fails due to insufficient wash resistance, especially hydrolysis under alkaline conditions. It should also be noted that waste disposal problems of fluorocarbon solutions must be viewed more critically in the future.
There is a need for an improved permanent hydrophobic finish that can be produced using limited amounts for coating forming monolayers or limited multilayers having good chemical and mechanical stability even in the presence of aqueous or aqueous-alcoholic solutions.